BTW, you said the performance difference of dio READ is 38% but Ithink it's 27.3 %, though it's still large.

> Pete Wyckoff's results> (http://www.osc.edu/~pw/papers/wyckoff-iser-snapi07-talk.pdf) are hard> to interpret. I have asked Pete which of the numbers in his test can> be compared with what I measured, but Pete did not reply.> > > The version of OpenIB might matters too. For example, Pete said that> > STGT reads loses about 100 MB/s for some transfer sizes for some> > transfer sizes due to the OpenIB version difference or other unclear> > reasons.> >> > http://article.gmane.org/gmane.linux.iscsi.tgt.devel/135> > Pete wrote about a degradation from 600 MB/s to 500 MB/s for reads> with STGT+iSER. In my tests I measured 589 MB/s for reads (direct> I/O), which matches with the better result obtained by Pete.

I don't know he used the same benchmark software so I don't think thatwe can compare them.

All I tried to say is the OFED version might has big effect on theperformance. So you might need to find the best one.

> Note: the InfiniBand kernel modules I used were those from the> 2.6.22.9 kernel, not from the OFED distribution.

I'm talking about a target machine (I think that Pete was also talkingabout OFED on his target machine). STGT uses OFED libraries, I think.